烘焙预处理对纤维素热解特性影响的研究

Effect of Torrefaction Pretreatment on the Pyrolysis Characteristics of Cellulose

以纤维素为原料,采用小型烘焙脱氧实验装置、热重分析仪(TGA)和热裂解色谱质谱联用仪(Py-GC/MS)研究了烘焙脱氧温度(200℃、250℃和280℃)对纤维素燃料品质和热解特性的影响,并采用分布式活化能模型(DAEM)计算了烘焙前后纤维素的热解活化能。结果表明,烘焙脱氧预处理降低了纤维素的氧元素和挥发分含量,减弱了纤维素的热稳定性,增大了碳元素和固定碳含量,提高了纤维素热值。烘焙先后纤维素的热解活化能没有发生较大的改变,然而烘焙后的纤维素在热解过程中容易发生交联反应而最终形成焦炭,并在快速热解中容易生成较多的左旋葡聚糖、糠醛和小分子物质。烘焙脱氧预处理改善了纤维素热解产物品质,有助于生物质的热解利用。

The effect of torrefaction temperature( 200 ℃,250 ℃ and 280 ℃) on the fuel quality and pyrolysis characteristics of cellulose were studied using a torrefaction experiment device,thermogravimetric analyzer( TGA) and pyrolysis chromatography-mass spectrum( Py-GC/MS). The pyrolysis activation energy of cellulose before and after torrefaction was calculated using the distributed activation energy model( DAEM). The results show that the torrefaction deoxidization pretreatment reduces the oxygen content,volatile content and thermal stability,increases the carbon and fixed carbon content,and improves the calorific value of cellulose. Torrefaction has not remarkable effect on the pyrolysis activation energy of cellulose. However,crosslinking reaction is easy to occur in the process of pyrolysis of the torrefied cellulose,leading to formation of coke,levoglucosan,furfural and small molecules. Torrefaction pretreatment improves the pyrolysis product quality,which is conducive to pyrolysis utilization of biomass.